public class sendmail{

List<Employee__c> email = [Select E_mail__c from Employee__c where E_mail__c != null];
public void sendmail()
   {
      Messaging.SingleEmailMessage email = new Messaging.SingleEmailMessage();
      string [] toaddress= New string[]{'email.E_mail__c'};
      email.setSubject('Testing Apex Scheduler-Subject');
      email.setPlainTextBody('Testing Apex Scheduler-Body');
      email.setToAddresses(toaddress);
      Messaging.sendEmail(New Messaging.SingleEmailMessage[]{email});
    }
}